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Hypoxia

The Doyle family farms along the Mississippi River in Iowa. Their corn and soybean crops grow in rich river soil created by centuries of sediment deposited by glaciers and the Mississippi's flood cycles. The Dauphin family lives near the Mississippi River's delta, which is south of New Orleans. Instead of land based crops, the Dauphins harvest fish, shrimp, and crabs from the river's rich delta waters. Both families rely on the river to make their living. And they find themselves pitted against each other for survival.

The "farmers of the sea" are facing a serious threat to their livelihood—hypoxia. Hypoxic waters contain too little oxygen to support aquatic life. Hypoxia begins when excess nutrients are carried to a body of water. The excess nutrients trigger huge algae blooms. (Algae are small aquatic plants that reproduce quickly, spreading or "blooming" in the water.) The blooms grow, die and decay. The decaying process uses up oxygen in the water, leaving too little to support other aquatic life. The hypoxic conditions existing in a huge area of the Gulf of Mexico have created the "Dead Zone."

Some research blames hypoxia directly on upriver farmers, like the Doyles. Why? Many land-based farmers apply nitrogen to their fields to boost plant growth and increase the size of harvests. Some researchers say that too much of this nitrogen is running off farm land into streams and rivers that feed the Mississippi River, ending up in the Gulf and triggering the cycle that leads to hypoxia and the Dead Zone.

What Can be Done?

Research suggests that farmers drastically cut the amount of nitrogen fertilizer they apply to their crops and plant buffer zones near streams and rivers. (Buffer zones are areas of vegetation planted between crops and waterways.) Farmers are resisting these suggestions because they say it is a double cut—they would lose crop land to create the buffer zones and have lower yields if they apply less nitrogen.

A more drastic suggestion is that millions of acres of farmland get turned back into wetlands. Wetlands act as a natural filtration system. They keep fertilizer runoff from getting into the water by absorbing the runoff.

Farm supporters point out that the chemicals they apply aren’t the only source of nitrogen, or the only problem. Animal waste contains nutrients, and urban landowners use chemicals as well. Upstream farmers want research to be done to see how dikes and channeling affect the river. They also point out that thousands of acres of gulf coast wetlands are lost each year, removing the natural nitrogen filters at the mouth of the river.

Until a solution to hypoxia is found that is agreeable to all those involved, the farmers of the land and the farmers of the sea will stay locked in their struggle for survival.

 

 


Explore More: Water Quality
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